Denzel Washington can't do noir. Well, maybe he can, but he doesn't in this stylish, tense, vivid, ravishing movie. The real-life Frank Lucas, on whose story the film is quite closely based, seems to have been ordinarily unpleasant, at least as one dispassionate magazine article had it in 2000.

Maybe Denzel wasn't asked to portray a nasty piece of work. Maybe he was asked, but couldn't bring it off. Who knows? It is just possible to see the portrayal as progress. Here is an attempt at a sophisticated black character played by someone who isn't Morgan Freeman. It's an advance on Samuel L Jackson's endless if enjoyable black monsters and Will Smith's and Washington's reassuring charm fests. But it really doesn't work.

Here we have a 70s gangster who is nice to his mother and anyone who is nice to him but who unblinkingly cuts down anyone who gets in his way. But he is a character who oozes so much charm and plain good-guy smileyness that his cold-blooded killing and his way of getting a living are profoundly improbable. James Cagney would be turning in his grave at so feeble an account of criminality.

It's not as though movies have not previously addressed the peculiarity of attractive crooks, nor had actors playing against type to intrigue us. Tom Hanks' Road To Perdition (2002) disguised his niceness very well. The perennially attractive Warren Beatty brought us credible veneered viciousness in Bugsy (1991). Cary Grant could parlay cool and good looks into the sinister. George Clooney hasn't tried yet and Mr Washington hasn't succeeded.

All gangster movies pose the delicious dilemma that you have to like a monster. Try the Tony Soprano comparison. Tony was such a brilliant character because you came to believe that this teddy bear sadist was aware that the code by which he lived was deficient and that his own life was deficient. He had lost the taste for whacking people. Or rather - and this is the important bit - he had lost the means to shelter himself from the plain wrongness of what he did. He went on doing it of course. He had his immediate and more distant family worlds to support.

Besides, he was an animal. He came from a long line of sociopaths who had lived all their lives in a sociopath culture. We believed that Soprano knew enough to realise that he was wicked, but lacked the moral equipment to say so out loud or to join the rest of us in getting a legitimate living in the real world. He was, as crooks and tarts say, "in the life" and locked there.

It is possible that Ridley Scott was making a mistake which is close to racist. Or rather, one which is reverse racist. That's to believe the descendents of slaves come from such a dysfunctional history that their appalling behaviour can be justified or any rate explained. Or, more bluntly, they have been so dumped-upon by society that they must be allowed to turn the tables any way they can.
Certainly, "gangsta" culture is endured, pandered-to, celebrated and imitated as though being black really does rewrite the rules of respectability.

There are certainly passages in American Gangster in which both the police and the Italian mobsters share a couple of prejudices: firstly that no black man could possibly be bright enough to be at the top of the drugs industry tree, and secondly that even if one was, he was being unconscionably cheeky. These racist attitudes were probably lobbed at us in the entirely justified hope that most of us would take our eye off the real moral ball straightaway.

And then there were the quite risible moments when an army of hick siblings chuck everything rustic and instead become accomplished urban mobsters. Again, there is not a scintilla of a suggestion that this was not exactly Seven Brides For Seven Brothers (1954). Naturally, the mother of the American Gangster is a delicious white haired old lady who asks no questions as to why she is suddenly living in the Big House. Mind you, even she - when the chips are down - suggests that it is unwise to be a cop-killer.

And then there's the little Puerta Rican moll and wife: she sleepwalks her way through the moral mayhem. She has the cheek to look intelligent and thoughtful, and only the teensiest bit troubled toward the very end when people are trying to kill her. There is even a bizarre shot at making out we are dealing with a Robin Hood who is giving addicts purer stuff, cheaper than the white brethren. He gets tough with someone who damages his brand by "cutting" his powder. Very MBA.

At first sight (whilst you're in the cinema) the back end of the film starts to get interesting. That's when our anti-hero Frank Lucas is brought to justice, and about time too. And of course his plea bargaining is interesting and challenging, as the real process must be. But even here, the moral underpinning of the story is close to absurd. Both the gangster and the policeman get on their high-horses about police corruption. Oh yeah, right. So now the black gangster is on the side of the angels because he works with the Nice Policeman to shop the Nasty Policemen (even though he had bribed plenty of the latter in his time).

So we can all go about with a skip in our step because the only thing that really matters is bringing bent coppers to book. Do that, and your murders are laundered nicely. This is especially true if you remember to prettily lose your temper whilst appearing to turn Queen's Evidence (or whatever) and you have a little outburst about the indignities inflicted on you and your people, blah blah. Pathetic, and way too late in the movie.

If you can forget all this, the film works a treat. It is an homage to efforts such as Serpico (1973). Rainy New York and steaming Hanoi are glutinous and slick. Boxing matches and Mafia mansions and nightclubs and drug dens are all full-on and in your face. You surf the grimness and glitz because both are relished. You spend a lot of time wondering whether Russell Crowe is at all convincing as a weirdo cop and then you think he may well be because he is so solidly unattractive, just as his wife seems to have come to believe.